TL;DR – nobody really knows. There’s way too many buttons on there to understand what on earth is going on.
“I cannot tell,” she returned, “but you may come with me, if you like. If Oz will not give you any brains you will be no worse off than you are now.”
“That is true,” said the Scarecrow. “You see,” he continued confidentially, “I don’t mind my legs and arms and body being stuffed, because I cannot get hurt. If anyone treads on my toes or sticks a pin into me, it doesn’t matter, for I can’t feel it. But I do not want people to call me a fool, and if my head stays stuffed with straw instead of with brains, as yours is, how am I ever to know anything?”
“I understand how you feel,” said the little girl, who was truly sorry for him. “If you will come with me I’ll ask Oz to do all he can for you.”
“Thank you,” he answered gratefully.
They walked back to the road. Dorothy helped him over the fence, and they started along the path of yellow brick for the Emerald City.
Toto did not like this addition to the party at first. He smelled around the stuffed man as if he suspected there might be a nest of rats in the straw, and he often growled in an unfriendly way at the Scarecrow.
“Don’t mind Toto,” said Dorothy to her new friend. “He never bites.”